Well, if Rose Quartz isn't Pink Diamond, SU fans are going to need another theory to latch onto! *Spins the wheel of theories.* And the winner is... Rose Quartz was not the one to kill Pink Diamond! And you can read all about it in the theory below!
WAIT WAIT WAIT. So Eyeball saw Rose Quartz shatter Pink Diamond. Which to begin with, I don’t believe. I do believe that is what she thought she witnessed. It’s already been proven that she got tricked by a shapeshifted gem pretending to be another gem (Amethyst as Jasper). So who says she hasn’t been tricked like that before right? Anyway, Eyeball said something to Steven in Bubbled like “I don’t care about the stupid shield all I remember is her massive sword” (or something alike, don’t quote me on that). BUT here is the thing. This indicates she saw no actual proof it was Rose Quartz, only someone who wielded her signature weapon but not her ACTUAL gem weapon: The Shield. Mind you, Bismuth said that the sword only cuts through the gems body but never the gem itself. So if PD got proofed, it means that whomever shattered her, had to shatter her other than via the sword. And besides me questioning what could shatter a diamond (besides another diamond) it also indicates that whomever shattered her had to use some serious force. The how’s and what’s are still unknown (as usual, *conservative voter voice* thanks Rebecca…) but to use a lot of force indicates some serious perseverance in this murder right? Okay to put my entire thing together: Someone murdered Pink Diamond, allegedly Rose Quartz. But what if someone was not content with the caste-system of Homeworld, someone who was at the absolute dirt layer of this construct, who shapeshifted into Rose Quartz to get close to Pink Diamond and take her down, someone who can wield a sword and has access to Rose’s armoury, someone who no longer shapeshifts after the incident, someone who had a severe emotional response to the mention of the act that Rose Quartz took the blame for, and who has been trying to make up for it ever since: “Why won’t you let me do this for you Rose?”